Conventionally, an AE (Acoustic Emission) detector that detects a warning of destruction by acoustic emission is described in JP 7-318457 A.
Moreover, another conventional AE detector measures the amplitude of AE generated in a machine to which the AE detector is attached and judges it as a warning of destruction when the amplitude becomes greater than a predetermined value.
However, the AE detector, which judges the warning of destruction simply by the amplitude of AE, sometimes misjudges a mere noise as a warning of destruction, posing a problem that certainty and reliability are low.